Natural Selection
by starisfairy
Summary: Mutants. They're thought of as the next big leap in humanity, but some things aren't always what they seem. You see, we humans are experts in the art of denial, even if the obvious is right in front of us. YYH/YGO/X-men Xover.
1. Chapter One

_**Disclaimer- I do not own Yu Yu Hakusho, Yu-Gi-Oh, or X-men. Nor do I own the full idea for this story. I was inspired by **_**Vaeru's- For Adoption: YYH x X-men Crossover**. _**I have also obtained permission from Kurome Shiretsu, a brilliant writer on this site, to use a few ideas from her story YYH/X-men story, 'Mission X'. Kurome Shiretsu also happens to be Vaeru's former account, so… yeah! Give her some love for me. She's at least half of the reason why this story exists.**_

* * *

_**natural selection:**_

–_noun_

_**The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.**_

.

**June 1st, 2010**  
**Bayville, New York**

Ororo Monroe glared at the folder lying at her desk with barely concealed exasperation.

It was late, too late to be working—and she was exhausted. Running a school proved to be quite a bit of work, and she didn't yet feel up to the challenge. Even after five years.

But the mutant numbers were growing by the day, and the school was needed more than ever. There were now a multitude of mutant programs and facilities popping up in the more major areas of the U. S., and there was beginning to be conversation on how to expand them into foreign territory.

And here she was, at the center of it all.

Of course, she had help—the government provided certain funds, and mutants were now legally under the Bill Of Rights. Not to mention the multitude of friends she had in high places. There was a team of engineers working on a better, more proficient way of finding mutants, and all was going well for the time being.

But sometimes, she still felt so lost.

She had been prepared for assumption of Charles Xavier's mantle for years before he had passed. Ororo had been his successor, his heir. And in a way, she had been his prodigy. Though no one had ever said it.

She had been the most stable, the most unobtrusive. She hadn't been the most intellectually capable—no, that was Jean's place; but she'd been right behind her. And she was more mentally balanced.

And so Charles had chosen her. He had showed her how to fill out the paperwork, and how to file cases. He had showed her everything that she needed in order to be his successor with ease.

But still, she wasn't ready. She wasn't sure she ever would be.

However, she'd come to terms with this fact a long time ago. There was no need to dwell on it.

Looking at the clock with a feeling of apprehension, she noted that it was already past eleven PM. She then looked at the—still closed—folder atop her desk. It was then that she assessed that grading her Senior's final essays would have to wait until tomorrow.

She had more pressing matters to attend to.

Opening the folder with rising trepidation (she had a nasty feeling that there was more than met the eye with this group, for this was the second time today that she had extensively read this particular file), she began to read.

The first file was on a certain Yuugi Mutou of Domino, Japan.

He was a thin boy of short stature. His clothes were decidedly eclectic, as was his way of wearing them. His hair was wild—spiky, colorful and long…but his eyes were what caught her attention.

They were large, the shape of almonds. And they were a brilliant, beautiful violet.

Even in a photograph, they were intense.

They were deep and kind and so very special. They were focused on the camera as he smiled a shy, awkward smile. She felt as though he were looking into her soul with those eyes.

And according to his medical file, they were_ natural_.

Quickly realizing with unease that those eyes were entrancing her, she turned the page abruptly.

Ryou Bakura was an unobtrusive, effeminate young man with a disarming smile and extremely pale skin. His hair was light—the color of her own ivory tresses—and it grew far past his shoulders in a shaggy, layered style. He was thin, too thin, and his limbs were long and lanky.

And his _eyes_.

They were beautiful, yes—the shape of almonds—but there was something dark and sad and lonely in his hazel-brown depths, something that was too knowing, too melancholy… and just by looking at him, it was obvious that he wasn't exactly a picture of health.

Reading his file didn't make it any better.

And once again, she found herself feeling relieved to move onto the next file.

The youth on this page was lean and tall, with long, thin limbs.

Shuuichi Minamino was admittedly effeminate—but his shoulders, while narrow, were also broad enough to betray his gender. He stood calmly, his posture self-assured, confident.

His smile was charming and polite… but his grass-green eyes were mischievous and disturbingly intelligent. Omniscient, almost.

And most of all, he was guarded. Too guarded. No matter how hard she tried to analyze him, she couldn't begin to guess what he was thinking.

It was unsettling.

And so she turned the page once more.

The laughing, mahogany eyes of Yuusuke Urameshi greeted her as he stared at the camera with a confident (bordering on arrogant) smile. He was a strong, relatively lean man, with a substantial physique and long limbs. His muscles were lean and hard—a street fighter's muscles.

His stance was arrogant and powerful, but Storm could still see the kindness shining through like a beacon. It was very obviously there, though many might not notice it. It was a strange sight to behold: a gruff, but kind young man. No more than a boy, really.

He was just barely an adult, by American standards.

Throwing an automatic glance at the clock, she let out a mental groan. It was nearly midnight, and she was still supposed to call a meeting and discuss the urgency of getting these boys to the Institute safely.

She skimmed over the last two files rapidly, in a hurry.

She then smiled wryly.

After all, it wasn't every day that you find out the world's most influential teenager was a mutant. Let alone his brother.

Seto Kaiba would not be pleased.

Closing up the rather large folder, she stood up regretfully. Her legs cracked, notifying her of how long she has been in the rather impersonal office chair. However, she ignored the pain as she used the intercom to call all of the current X-men into the conference room.

She then grabbed the folder and left the room, she had to get the meeting hall ready for presentation.

As it turned out, they were going on a little field trip.

* * *

_**NOTES:**_

_**Okay, so as you see, I've screwed with the timelines of both YGO and YYH quite a bit. I'm not sure if I've screwed with X-men, as there aren't many dates documented in the movie series. Besides, both animes seem to be relatively high-tech, so it's really more realistic for them to take place in the 2000's, anyway! XP In essence, the entirety of the fanfic starts of in 2010, though there MAY be flashbacks.**_

_**All of the anime characters are (physically) aged from 17-20 years of age.**_

_**The timelines for the shows/movies go as follows:**_

_**Yu-Gi-Oh- **__the main characters were born in 1992, not including the younger YGO characters. They are 17-18 years of age. This story takes place around a year after the end of the series._

_**Yu Yu Hakusho-**__ the main characters were born (or physically look like they were born) in 1990-91, not including the older characters. The characters physical ages are 19-20. This story takes place around a year after the series._

_**X-men- **__this story takes place five years after X-men: The Last Stand._

_._


	2. Chapter Two

_**Disclaimer- I do not own Yu Yu Hakusho, Yu-Gi-Oh, or X-men. Nor do I own the full idea for this story. I was inspired by **_**Vaeru's- For Adoption: YYH x X-men Crossover**. _**I have also obtained permission from Kurome Shiretsu, a brilliant writer on this site, to use a few ideas from her story YYH/X-men story, 'Mission X'. Kurome Shiretsu also happens to be Vaeru's former account, so… yeah! Give her some love for me. She's at least half of the reason why this story exists.**_

* * *

_**natural selection:**_

–_noun_

_**The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.**_

* * *

_**March 7th, 2010  
Domino, Japan**_

There was danger looming on the horizon. He could tell. He didn't know how or why, but he could tell.

He could feel it in the air; he could see it in how the clouds moved across the sky. He could see it in his dreams, dreams riddled with darkness and shadows and fear. And it was always lurking at the corners of his eyes.

Bakura Ryou had learned to trust these instincts. Even when he didn't like what they were telling him. Because, whether he liked it or not, they were always true.

Always.

He can remember, as a child, getting these instincts from time to time... but they had ceased to exist a few months after Amane had died.

He'd thought they were gone for good, these feelings. These feelings that he could know almost anything that he wanted to.

But now… they were back. And this time, they were out of control.

Looking back, he can remember the exact date of when the premonitions started. It was September 9th, 2009. Precisely seven days after his seventeenth birthday.

It had been a strange and twisted dream, one in which everything was blurry, colorless, and engulfed in shadows. The silhouette of a figure, presumably female, was crossing the street. And then... the shadow of a speeding car appeared out of nowhere.

She had never stood a chance.

He had woken up with a jolt, feeling muddled.

… That is, until he saw the clock on his bedside table.

He was going to be late for school.

So, he rushed around his little apartment, completely forgetting about the disturbing dream, ignoring the dark shadows lurking in his peripheral vision. He couldn't be late. Not again. Not after he finally had his life together.

At this point, his future was at stake. He didn't have time to worry over night terrors. He was used to them by now.

And as the days went by, he forgot about the dream altogether.

After all, how was he to know that this dream, in particular, would come true?

But a little over a week later, on September 16th, 2009, a classmate of his was hit by a car. Her name was Nakamura Ami, and she died on impact. She was an Honors Student, part of multiple clubs. She was one of the best students at Domino High School, and she'd known where she was going with her life.

She had wanted to be a Psychologist once she graduated from Tokyo U.

Now… it would never happen. Her dreams would never be realized.

The entire school had mourned over her, the girl that had so much going for her, the girl that had so much potential. The girl who's life had ended much too soon.

Nakamura Ami's life hadn't even started yet.

And Bakura Ryou was riddled with guilt.

He'd been pushing the very notion that something strange was happening to him so vehemently—that he became blind to the obvious. If he had just dug _deeper_, gone just a little_farther_ into his psyche... maybe she would still be alive.

He'd been selfish, preoccupied with his desire for normalcy. And now a girl was dead. And he knew that he would never, _never_ be able to forgive himself, for this wasn't the first time he had ignored his instincts.

No, it wasn't the first time, and the last time that he had failed—had cost him a lot more than he could've ever imagined: the center of his entire universe. He didn't want to see anyone else pay for his mistakes.

From then on, he paid close attention to the premonitions, even as they grew more clear, more gruesome. More _terrifying._

On the best of nights, he only got six hours of sleep. And most of those hours were riddled with fear and terror and _pain_.

Sometimes, he wondered why this had happened to him, why he had ended up with this… ability. Especially after everything else that had occurred throughout his existence.

Sometimes, he truly entertained the idea that maybe, just _maybe—_he was cursed. And maybe he was. All he knew was that peace never seemed to last long for him.

Given this hypothesis, why should now be any different?

.


	3. Chapter Three

_**.**_

_**Disclaimer- I do not own Yu Yu Hakusho, Yu-Gi-Oh, or X-men. Nor do I own the full idea for this story. I was inspired by **_**Vaeru's- For Adoption: YYH x X-men Crossover**. _**I have also obtained permission from Kurome Shiretsu, a brilliant writer on this site, to use a few ideas from her story YYH/X-men story, 'Mission X'. Kurome Shiretsu also happens to be Vaeru's former account, so… yeah! Give her some love for me. She's at least half of the reason why this story exists.**_

* * *

_**natural selection:**_

–_noun_

_**The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.**_

* * *

_**May 30, 2010**_

_**The Beach Of Memory, Japan**_

Today was peaceful, to say the least.

It was mid-afternoon, around four PM. The sun was shining brightly in the clear, pale blue sky, and there was a light breeze moving throughout the air.

Yes, today was very peaceful, indeed.

Minamino Shuuichi, known as Kurama to his friends—as well as his enemies—looked at the scene in front of him with amusement.

The sight before him was easy to find amusing in some sort of way: a ball of entangled limbs, obviously engaged in—rather _violent—_combat. Whether it was playful or not, a stranger would never know. But nonetheless, a fight between Urameshi Yuusuke and Kuwabura Kazuma was truly something to behold.

Trash talk and super-speed included, of course.

Actually, a typical, everyday person would, quite honestly, be terrified of this spectacle. However, no one present was a typical, everyday person, and none of them were even_remotely _terrified.

In fact, this was _their _typical, everyday spectacle. Or, at least, as typical and everyday that the motley group could be, considering who they were.

Hence, his reason for amusement.

This was one of the only things that was ever routine for them. Though, life for the group _had_ become increasingly normal as of late.

Genkai, still alive and pushing seventy-nine, was always up for a fight or one of her legendary 'training sessions from hell', as Yuusuke had dubbed them; Yuusuke's _ramen_ stand was a roaring trade in town; and both Keiko and Kuwabara had started at two of the best universities in Tokyo, studying teaching and medical studies respectively.

As for himself, Kurama seemed to be fitting into his position at his stepfather's company quite nicely. It was a tad _mundane_, but that particular issue wasn't unexpected. The choice had been his. He'd chosen to live the remainder of his human years _as_ a human. It was as simple as that.

His mother had, at first, been slightly dismayed when he'd decided to forego college temporarily. But his invitation to _Meioh_ _Private University_ was longstanding, and he was allowed to transfer in at any point in time.

Upon hearing this, she'd seemed quite happy with the arrangement. After all, how often does one get a good and sturdy career before even graduating from high school? It was much too excellent of an opportunity for him to miss out on.

And so here he was, sitting with his closest friends on a sunny, warm afternoon. The mid-spring breeze was pleasantly cool, and it played across his face, ruffling his long, crimson hair and making his locks flutter.

Tearing his eyes away from the spectacle before him—the one in which Yuusuke was succeeding in beating Kuwabara into a pulp while attempting to suppress the majority of his_Reiki_—he inspected the rest of the group.

Keiko, Yukina, and Botan were standing by the water, trying in vain to ignore the sounds of the fight between Keiko's fiancé and Kuwabara going on a few yards away. They were giggling softly, obviously talking about the brand new engagement ring that was on Keiko's finger. It glinted in the sunlight, shining beautifully…

It seemed that everyone was content at present.

Genkai was casting glances towards her 'favorite dimwit' with well-concealed fondness as she observed his fighting method.

Hiei, having earned a well-deserved break from _Makai_ Border Patrol, was perched in the tree that Kurama was currently leaning on. His expression was stoic, bored. Kurama, however, knew differently. Hiei, too, was happy. Well, as happy as he was ever going to get.

And, as always, Kurama couldn't help but feel… skeptic. He'd never been particularly fond of optimism, and that wasn't going to change with his new-found life choices.

It had been a year since Yuusuke had come back from the Makai. And nothing eventful had happened whatsoever. The portal between the worlds was opening successfully, and the Border Patrol had kept the more _dangerous _demons under control.

The worlds were slowly integrating.

And Kurama couldn't help but feel as though this strange amount of peace was just an interlude to something much darker.

"_Kurama."_

Kurama didn't look up. He didn't need to.

One does not exchange social graces when telepathically communicating. It's unnecessary.

"_What is it, Hiei?"_

"_You're conflicted. Why?"_

"_It doesn't matter. I'm merely being pessimistic."_

Kurama said no more, and Hiei didn't answer.

A shadow passed over the beach, casting a dull, gray light onto it. He looked up, his eyes narrowing imperceptibly as he took note of the large, gloomy cloud that had appeared, seemingly from nowhere.

Subconsciously, he fingered a rosebud in his hair. It was part of an arsenal that he kept around… just in case something happened.

Realizing what he was doing, he dropped his hand.

"_It's going to rain."_ he projected.

"_Hn."_


	4. Chapter Four

_**Disclaimer- I do not own Yu Yu Hakusho, Yu-Gi-Oh, or X-men. Nor do I own the full idea for this story. I was inspired by **_**Vaeru's- For Adoption: YYH x X-men Crossover**. _**I have also obtained permission from Kurome Shiretsu, a brilliant writer on this site, to use a few ideas from her story YYH/X-men story, 'Mission X'. Kurome Shiretsu also happens to be Vaeru's former account, so… yeah! Give her some love for me. She's at least half of the reason why this story exists.**_

* * *

**natural selection (noun)-**

_**The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.**_

* * *

_**May 24**__**th**__**, 2010**_

_**Domino, Japan**_

.

He awoke abruptly, chest heaving and heart beating with a worrying speed. He breathed. And then, slowly, he forced himself to sit up. It was only a dream, after all? Wasn't it?

That was what Mother had told him all of those years ago, back when he was still a child and things were still simple. Now, all that he was doing was lying to himself.

He rose from bed with great care, attempting to avoid the rush of dizziness that he knew was on its way. He waited for it to pass. He was used to it by now.

Casting a glance at the clock beside his bed, he wasn't surprised to see the time- four AM. He'd only gotten three hours of sleep tonight, but there was no use trying to sleep more now; all that awaited him were nightmares and he had to be at school in three hours.

And so he grabbed his uniform by his closet, laid in onto his bed, and stepped into the bathroom. Unwillingly, his eyes were drawn towards the mirror near the sink, towards his reflection. He had shadows under his eyes- but those weren't the only shadows that lurked nearby.

He was used to that, too.

.

He picked at his _bento_ with little interest, his thoughts elsewhere and filled with anxiety. He didn't understand _why _he felt this impending sense of doom, but it worried him- especially given the recent circumstances. It kept creeping up on him when he least expected it to.

Suddenly, he felt as though he was being stared at. He looked up from his lunch, searching for the source.

Oh. It was Yuugi. He watched from afar with a faint concern on his features and smiled when Ryou waved him over, making his way towards him and sitting down in the shade of a nearby tree.

"Hello, Yuugi-_kun_. How are you today?" Ryou smiled disarmingly, hoping that Yuugi hadn't been worrying over _him_.

"I am good, and you?" He grinned his own grin in return.

"I am fine. Thank you."

"Anyway, I came over to ask you if you wanted to join us all next week? We're going to Tokyo." Yuugi invited, looking rather anxious himself, "I tried calling yesterday, but you didn't answer. We started planning it last Friday during the study session."

"Once again, I apologize for being unable to attend. I had work."

"No big deal! So, do you wanna come?" Yuugi looked excited now, bouncing with a childish glee.

Ryou thought it over. He hadn't spent much time with Yuugi-_tachi _in awhile save for weekly study sessions that he led, so perhaps it would be nice. Yuugi certainly wanted him to come.

"Sure." He relented, a real smile coming to his face this time.

"Oh, good! We leave on Friday- you know, in celebration of summer break! It'll be great! I'll call you with the details later today, okay?" with this, the bell rang- signifying the end of break.

"That's fine, I'll talk to you then."

And with that, Yuugi ran off to find his friends.

Yes, it would be nice to go to Tokyo for the weekend- he had vacation hours at work, and he needed the break. Maybe he'd finally be able to shake that feeling of foreboding and escape the premonitions. It was worth a try.

Besides, he hadn't visited Mother's and Amane's graves in awhile. It was about time.

.

_**June 2nd, 2010**_

_**Bayville, New York**_

.

She almost regretted calling her teammates in so late at night- it was going on one am and the room was filled with the rubbing of eyes and growls of frustration.

Even Marie- soft, even-tempered Marie, seemed irritable. A little girl no older than three rested her head on her shoulder, clinging to her tightly with wide, blue eyes and an iron-clad grip.

"The alert woke Jez up," Marie murmured, irritation evident in her light, southern drawl and eyes simply _daring _someone to comment on the child's presence. It couldn't been easy to get a three-year-old to sleep, let alone one like Jezebel. She was never one to sit still.

"I apologize, Marie, but something important has come up." turning the projector behind her on, Ororo placed a set of pictures from the files that she had been studying onto the glass.

More people arrived and soon all of the seats around the round table was full, leaving many expected gazes to rest upon her. And so she began, "As I know that you are all aware of, there has been a recent spike in the activation of the mutant X-gene among adolescents and children- as well as, occasionally, adults."

Kitty spoke up, her hair touseled and pulled up into a messy bun- _bedroom hair, _"Has there been any news, then? Do you know what caused it yet?"

"No." Ororo resisted the urge to sigh, "However, as you all know- the source of the mutation appears to be coming from somewhere near Japan. That is where the most reports of the gene are coming from."

Everyone in the room- Kitty and Bobby and Marie and Logan and even little Jezebel- listened with rapt attention.

She sighed, "Unfortunately, there have been other reports of activity from there as well from different sources." a pause, "The Brotherhood has returned and is recruiting. They have targets."

The atmosphere grew tense immediately as the reason for Ororo's impromptu meeting became clear. An unspoken question rose to the tips of everyone's tongues.

"We leave tomorrow afternoon."

* * *

**Author's Note:**

**Wow, it's been awhile. I apologize. Our old laptop crashed last summer, causing me to lose a lot of files. The original versions of this story were among those, and they were going to take too much money to recover. I was hoping that we'd eventually be able to recover them, but we never did. I was waiting until then to work on this story.**

**However, since they haven't been recovered and it's been so long- I decided that I had to just... write it anyway. So, here I am! **

**I also republished the first chapter, which was fourteen pages, as three different chapters. So yes. **

**Please review! I'm back for now. :) (With a new penname- previously The Amber Raven.)**


End file.
